Control mechanism



NOV 18, 1952 H. A. NEUMAN 2,613,294

CONTROL AImxscmNIsn/l Filed Sepb. 19, 1951 2 SHEETS-SHEET' l au i/fzg ZZ,

#feser ,4. Mea/ww ATTORNEYS NOV 18, 1952 H. A. NEUMAN 2,618,294

' CONTROL. MECHANISM Filed Sept. 19, 1951 2 SHEETS- SHEET 2 INVENTOR. /iefer 4 050/444/ Patented Nov. 18, 1952 UNITED CONTROL MEOHANISM Herbert A. Neuman, Wrentham, Mass., assignor to The Foxboro Company, Foxboro, Mass., a corporation of Massachusetts Application September 1951, SerialvNo. 247,275

This invention relates to apparatus for providing Aa variable restriction to the ilow of fluid in or ink association with automatic controllers, and

moreparticularly to restriction apparatus of particular conguration and Operation.

It is an object of this invention to provide new and Iimproved uid flow variable restriction apparatus.

Itis another object of this invention to provide yfluid iiow variable restriction apparatus with a Bourdon type tube of vnew and improved ooniiguration.

It. Lis a further object of this invention to provideziiuid flow variable restriction apparatus with automatic control of restriction to uid flow in 'a Bourdon type tube.

These` and other objects of the invention will be inpart pointed out and will be in part obvious from. the text.

This invention, accordingly, consists of the features of construction, combinations of elements. and arrangements of parts as will be exemplified in the structure to be hereinafter more fully described 'and the scope of the application of which willbe set forth in the accompanying claims:

In the accompanying drawings:

Figure I is a front elevation, in partial vertical f'section. of a structure embodying this invention;

Figure II is a side elevation of of Egure I; and

Figure III is a vertical central section of a portion of the structure of Figures Ivand II, taken as cin line III-III in Figure II.

The invention in its preferred form makes use of arcuately shaped restrictor with curved portions resembling sections cut from ordinary Bourdon tubing. Variations in the restricting effefct upon fluid ow therethrough may be is unbent, the same pressure drop will produce .f

a larger iluid ow because the resistance to fluid flowtherethrough is reduced.

It has been discovered that the relationship between the amount of bend in the tube and the ow through it is a proportional one. The tube,

the structure trol of fluid flow through the tube.

2 claims. (ci. 13s-45) in being bent, is allowed to follow its natural ar' cuate path, as it would if moved by internal pressures, assuming it to be otherwise free to bend and unbend. Thus, for any given arrangement: of parts and pressure drop, each unit of bending movement will produce a proportionally related change in the uid ilow through the tube.v This proportion may be varied by adjustmentl as will be explained later herein.

This invention provides means for automatically bending the Bourdon type tubing in re spense to a control signal as an automatic con- 'Ihe device y is a throttling type of valve with small capacity. As an example, it can handle 2.5 cc. per

j' minute of water under pressure drop of 2.5 to

Y operatively connected by a link I2. The bellows unit II) comprises. a generally cylindrical bellows I3 with a cylindrical cover can I4 containing the bellows. The bellows has a closed, movable end I5 and an open, fixed end I6. The can I4 also has a closed end, Il, and an open end, I8. The can and bellows are assembled on the same cylindrical axis, with the closed ends adjacent each other and the open ends secured to each other in pneumatically sealed relation. Thus a pneumatic pressure chamber is provided outside the bellows and within the can, and this assembly of bellows I3 and cover can I4 is rigidly mounted on a support plate I9 by means of screws 20. y

The closed end of the cover can I4 is provided with a pneumatic signal input pipe 2|. Pneumatic signals are applied to the bellows I3 through this pipe 2| from anysuitable control source, to automatically move the bellowsin representation of the input pneumatic signals. The bellows movement is limited by a'motion stop assembly. generally indicated at 22. The movable end I5 of the bellows has an. opening 23 therethrough which is closed off by a threaded member 24 extending therethrough. The bellowsv end I5 is clamped betweena shoulder 25 on the member 24, and a nut 26 threaded on the member 24 inside the bellows.` The threaded member 24 extends out through an opening 21 in the end I l of the cover can I4. Secured in the Opening 21 in pneumatic seal relation therewithis a 'cylindrical sleeve 28 as a stop for bellows motion. The

bellows I3 and the responsive amount of bend in the restrictor. Also, With a particular proportional arrangement established, adjustment may be made to vary the zero, or desired starting point of the tube bending action. It will be seen that for any given curve form in the tube as at 49, a change in the angular relation between the link I2 and the restrictor tube Il will provide a new proportional relation. Also, for any given angular relation between the link I2 and the restrictor tube I I, a change in the curves 49 will change the zero, or starting point of the tube bending action.

These adjustments, within the structural and dimensional limits of the device, may be accomplished by one or more of the adjustments, singly or in combination, as is convenient, desirable, or necessary. The adjustments are: moving the tube II in and out of the hexagonal bar 43, pivoting the hexagonal bar, and bodily moving the hexagonal bar along the slots 46 in the U legs 4,2, This bodily movement of the bar 43 and the tube length adjustment are essentially zeroing adjustments, and the pivoting of the bar 43 is essentially a proportion adjustment.

This invention, therefore, provides apparatus for providing a variable restriction to the ow of uid in or in association with automatic controllers, with particular reference to restriction apparatus of particular configuration and operation.

As many possible embodiments may be made of the above invention and as changes may be made in the embodiment described without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. A pneumatic flow control unit comprising an arcuately bent restrictor tube open to uid fiow at both ends, a bellows, movable in response to a pneumatic signal, and a mechanical connection between said tube and said bellows to translate said bellows movement into bending movement in said tube to vary the restriction thereof as a control of uid ow therethrough.

2. In a pneumatic control unit, a uid flow restrictor of Bourdon type tubing, said restrictor being bent in a double hook configuration, with the ends of the tube forming the Shanks of the hooks, the curved portions of the hooks providing duplicate curved and flattened metering sections in the tube, and an intermediate section of the tube joining said metering sections and being flattened at right angles to the flattening of said metering sections, a bellows, movable in response to a pneumatic signal, and a mechanical connection between said tube and said bellows to translate said bellows movement into bending movement in said tube independently of fluid pressure therein, to vary the restriction of said tube as a control of fluid ow therethrough.

HERBERT A. NEUMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,422,921 Nier et al June 24, 1947 2,432,082 Bilyeu Dec. 9, 1947 

